Biodegradable polymer blends of poly(lactic acid) and starch

Abstract

Poly(lactic acid)(PLA) and starch were melt-blended using a twin screw mixer. To improve the toughness of blends, poly(epsilon-caprolactone) (PCL) was added up to 30 wt%. Blends were characterized by DSC thermal analysis, tensile test, morphological analysis and ATR IR spectroscopic analysis. The addition of starch gave little influence on thermal properties. In particular, at the starch content of 5 wt%, the crystallinity of PLA were the highest. The addition of starch resulted in reducing the tensile strength and elongation ratios. PCL was found to be effective in improving toughness. ATR IR spectra showed that the C=O band of PLA shifted when starch was added, indicating that some hydrogen bonding formed between the ester group of PLA and the hydroxyl group of starch. Morphological results by polarized optical microscopy showed that the size of the spherulite became smaller and less regular as the content of starch increased.